Sore on back and lots of hairloss, please help

[Mole]

Hello, our 4 year old male rabbit is shedding his hair, which is normal as the season is changing here.
However when brushing him today I noticed a bald patch with a red sore. I will try and upload some pics.
We keep him inside in his cage over night and when the weather is dry and warm enough he's free in the garden most of the day.
My only guesses is that he's got really itchy, as his skin around his neck looks a little flaky and lots of his hair is malting, and he's bitten himself. We sometimes see him do that when he's grooming but he's never ended up bleeding or having a sore from it so we're quite worried.
Any ideas please?

 

[Mole]

 

[Mole]

 

[JBun]

Flaky skin often means there is a mite infection, which would need treatment with ivermectin or Revolution(selamectin). I prefer the Revolution as some rabbits can have a sensitivity to ivermectin, but you do have to get a prescription for revolution from the vet. Make sure to see an experienced rabbit vet. Dosing info for revolution is in the second link.
http://www.medirabbit.com/EN/Skin_diseases/Parasitic/furmite/fur_mite.htm
http://wildpro.twycrosszoo.org/S/00dis/Parasitic/Cheyletiellosis.htm

https://rabbit.org/vet-listings/

 

[Mole]

Flaky skin often means there is a mite infection, which would need treatment with ivermectin or Revolution(selamectin). I prefer the Revolution as some rabbits can have a sensitivity to ivermectin, but you do have to get a prescription for revolution from the vet. Make sure to see an experienced rabbit vet. Dosing info for revolution is in the second link.
http://www.medirabbit.com/EN/Skin_diseases/Parasitic/furmite/fur_mite.htm
http://wildpro.twycrosszoo.org/S/00dis/Parasitic/Cheyletiellosis.htm

https://rabbit.org/vet-listings/

Thanks so much for the reply, when he sheds his fur his skin normally gets a bit dry like this so I wondered if it was that. It's the sore that's unusual but he does groom himself a lot so mayb bit himself.
He's not with any other pets so not sure where the mites would've come from?

 

[Popsicles]

If he is free in the garden he could pick up mites or fleas from wild animals, as they can stay in the grass for a while.